Preparation,Microstructure And Properties Of HEA-Ti Alloy By Spark Plasma Sintering

Titanium and titanium alloys are important structural materials and play an irreplaceable role in many fields such as national defense,aerospace and automobile industries.The preparation of titanium alloys by alloying is a very effective way to improve the properties of such materials.And the convenient method will also be a key topic of titanium alloy research now and in the future.In this paper,the principle of continuous instantaneous liquid phase sintering is used to prepare HEA-Ti series alloy materials by spark plasma sintering.The microstructure and mechanical properties change before and after,and the research results show that:（1）In this project,four samples of（HEA）_2.5Ti_97.5,（HEA）₅Ti₉₅,（HEA）_7.5Ti_92.5 and（HEA）₁₀Ti₉₀ with Cr Mn Fe Co Ni high-entropy alloy added to titanium were sintered at 950℃～1100℃The best densities of the prepared samples reach 96.9%,97.4%,98.1%,and 98.2%,respectively,which are almost fully dense,while the density of pure titanium materials without HEA addition under the same process is only 91.2%.The analysis believes that this is because the temperature and time of the reaction of each alloy element in HEA and Ti to form a liquid phase are different,so that a short liquid phase is continuously generated during the sintering process,forming a continuous instantaneous liquid phase sintering process,which can effectively reduce the sintering process.The temperature increases the density,and the experiments in this topic show that with the increase of the sintering temperature,the density of the material increases gradually.（2）After ball milling and mixing,the high-entropy alloy powder is dispersed around the titanium matrix.After sintering,the matrix titanium presentsαphase,and the original high-entropy alloy region presentsβphase,and theβphase is distributed around the original powder boundary in a network structure,and the network structure increases with high entropy.The alloy content increased gradually from quasi-continuous to continuous,forming an inhomogeneousα+βtwo-phase structure.The highest tensile strength of titanium alloys reaches 600MPa,686MPa,727 MPa and 707 Mpa,respectively,and the elongation at break is13.4%,12.7%,10.8%and almost no plasticity,respectively.Under the same conditions,the pure titanium material prepared without adding high-entropy alloy has the highest tensile strength.In contrast,the tensile strength of the sintered HEA-Ti series alloys increased by up to 90.3%.（3）The（HEA）_7.5Ti_92.5 alloy material with the most excellent comprehensive mechanical properties in the sintered state was subjected to solution aging heat treatment.In the solid solution stage,all the high-entropy alloy elements were dissolved into the matrix to form a singleβ-phase structure.At this time,the tensile strength of the sample was 625 MPa,and it has almost no plastic deformation ability.After aging treatment,it is transformed into a small granularβphase dispersed uniformly on theαmatrix,forming a uniformly distributedα+βtwo-phase structure.At this time,the tensile strength of the sample reaches 967 MPa,which is153%higher than that of pure titanium,while maintaining a 7.5%elongation at break.mechanical properties.